Cancer
What is already familiar, instinctive, and ready to be carried forward.
Leo
What is arriving, stretching the old shape, and asking for a new response.
A cusp is best understood as a threshold image: Cancer's water cardinal quality meets Leo's fire fixed quality. The Sun is still in one sign at a time, while the neighboring symbolism can describe the season around it.
Cancer brings
Cancer is ruled by Moon and speaks through water cardinal movement. Its familiar lesson is about the caregiver.
Leo arrives
Leo is ruled by Sun and changes the texture toward fire fixed expression. Its invitation is to practice the sovereign.
A boundary, not a loophole
If you were born near a sign boundary, use an accurate birth time and place when a precise chart matters. The cusp language can be a useful metaphor, but it should not replace the actual Sun sign.